This work was carried out during the two successive summer seasons of 2013 and 2014 at
a Private Vegetable Farm in El-Khattara Distract, Sharkia Governorate, Egypt, to study the effect of different nitrogen rates and whey protein hydrolysates (WPH)concentrations as foliar application on growth, enzymes, antioxidants, yield, tuber root quality and storability of sweet potato cv. Buregard under sandy soil conditions using drip irrigation system. Fertilizing sweet potato plants cv. Buregard grown in sandy soil with N at 60 kg/fad., and foliar spray with 0.15% WPH increased number of branches/ plant, leaf area/plant and shoots dry weight/plant, N, P and K uptake by shoots, average weight of tuber roots, marketable yield and total yield, TSS and total sugars as well as improved storability of tuber roots of sweet potato. Whereas, fertilizing plants with 80 kg N/fad., and spraying with 0.15% whey protein increased vine length, total chlorophylls in leaf tissues, peroxidase enzyme and antioxidants in shoots, starch content in tuber roots of sweet potato. On the other side, the highest concentration of glutathione oxidase enzyme in shoot and carotene content in tuber roots were recorded by the interaction treatment between 40 kg N/fad., and spraying with 0.15% whey protein. The study recommends  by using nitrogen fertilizer at 60 kg/fad., and spraying with 0.15%  whey protein to increase sweet potato  yield   grown in  sandy soil.